Aviation safety investigations & reports

Boeing Co 717-200, VH-IMD

Summary

Prior to descent into Coolangatta, the crew of the Boeing 717
aircraft noticed a low right hydraulic quantity warning. After
following the abnormal checklist and turning off the right
hydraulic system, the pilot in command decided that, due to the
rudder reverting to manual mode and the loss of operation of two
ground spoilers, he would divert the aircraft to Brisbane where a
longer runway was available. After advising Brisbane Air Traffic
Control of the hydraulic failure, and that a faster than normal
landing would be carried out, the airport's emergency services were
placed on standby.

With the right hydraulic system turned to the OFF position, the
aircraft's landing gear had to be manually lowered using the
emergency gear extension lever. That operation did not close the
main landing gear doors after the landing gear was extended. In
accordance with the abnormal check list an attempt to close the
doors was conducted by the crew after receiving the green down and
locked indication for the landing gear. However, following the
selection of the right hydraulic system to ON, a rapid drop in
hydraulic fluid quantity was noticed so the OFF position was
immediately re-selected before the doors had closed.

As the aircraft touched down, the main landing gear doors
contacted the runway surface. Although the doors were fitted with
non-sparking polyurethane rest bumpers, the runway centerline
lights were contacted creating sparks that were observed by ground
personnel. The aircraft was then brought to a halt on the high
speed taxiway where an engineer was requested to manually close the
main landing gear doors. Following closure of the doors the
aircraft taxied to the terminal. The abnormal checklist stated that
the aircraft is not to be taxied but may be towed after landing
gear safety pins had been fitted and main landing gear doors
closed.

An inspection of the aircraft by the operator revealed that a
hydraulic pipe from the right engine driven hydraulic pump had
failed at its brazed fitting, resulting in the loss of hydraulic
fluid from the right hydraulic system. As this was not the first
time that the operator had experienced such a failure of hydraulic
pipes, the aircraft manufacturer was contacted. It was determined
that the pipes in the area of the rear fuselage were being
subjected to vibration from the engine driven hydraulic pump, which
in some cases resulted in the fracturing of the pipe fittings.

Safety Action

Local safety action

As a result of the investigation, the following safety actions
were carried out:

The operator issued a memo to its engineering staff highlighting
the need for:

extra vigilance when inspecting the rear fuselage area;
and

all hydraulic fluid leaks to be treated as potential total
hydraulic failure and to be reported to maintenance watch.

The engine buildup unit contractor issued Service Bulletin, Rohr
SB R715.29-001 on 9 November 2001, that provided instructions to
install a pulsation attenuator to each engine driven hydraulic
pump.

The airframe manufacturer issued an All Operators Letter (AOL)
717-048 on the 18 January 2002, recommending that operators install
the hydraulic pump outlet attenuator (via Rohr Service Bulletin
R715.29-001) to minimize hydraulic system vibrations.